Telephone system



(No Model.)

J. CRAWFORD &YJ. B. KER.

TELEPHONE SYSTEM.

jpg! Patented-Jan. 3, 1888.

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UNITED STATES PATENT OEEICE.'

JOHN CRAVFORD, READING, AND JOHN BALFOUR KER, vOF HARRIS BURG, PENNSYLVANIA.

TELEPHONE SYSTEM.

SPECIPCATION forming part ofnLettei-s Patent No. 375,925, dated January 3, 1888.

Application filed Mart h 2-1, 1887.

To (LZZ whom t may concern:

Beit known that we, JOHN CRMVEORD, a citizen of the United States, residing at Reading, in the county of Berks and State of Pennsylvania,` and JOHN BALEOUR KER, a subject of the Queen of Great Britain, residing at Harrisburg, in the county of Dauphin and State of Pennsylvania, have jointly invented a certain new and useful Improvement in Telephone Systems, oi' which the following is a specitication.

Our invention relates to switclrboards for telephone'eXchaugesin which double-jacks are employed accessible from both sides of the board, so that connection may be made with a line by an operator on either side ofthe board; and our object is mainly to increase the simplicity and convenience of construction of switclrboards of this character.

To this end our invention consists in the novel devices and arrangements, hereinafter set i'orth and claimed.

Our invention is illustrated in the accompanying drawings, in which Figure 1 is a front elevation of a switch-board section embodying said invention with some of the jacks shown in dotted lines; Fig. 2, a vertical section thereof on line 2 2 of Fig. l; Fig, 3, an enlarged ele ration lof one ofthe springjacks; Fig. 4, a section thereof showing a modification employed for multiple switch-board systems; Fig. 5, a view ot' a plug which wc may use, with its handle in section; Fig. 6, a section of a switchboard with a modified 'way of attaching the jacks thereto; Fig. 7, a section on the line 7 7 of Fig. 6; Fig. 8, a section of a switch-board with another form of spring'jack; Fig. 9, a sec tion on line 9 9 of Fig. 8, and Figs. l() and 1l illustrate another form of spring-jack.

Referring first more especially to Figs. l to 5, inclusive, A and A are boards, made of wood or any other suitable insulating material. These are secured together, back to back, in a manner to be presently described, and may be supported in a vertical position in any desirable way. Each of these boards has apertures a or a through it, placed opposite each other, there being an aperture in each board for each subscriber of the system. Between the boards are placed the jacks. These consist, prefer- VSerial No. 232,21U- (No madel.)

to the body B by a screw, f, is the dat spring C, which passes around the body and at its free end rests normally against the screw c, so that the circuit from the subscriberto his annunciator-drop is normally closed at this point. The line from the subscriber is indicated by the wire 1, connected to the jack and the line leading from thejack tothe -annuuciator, and thence to ground by wire 2, Fig. 3.

The body A of the jack has a hole, g, for the reception of theplug, and an aperture extends up from this hole through' the body, in which is loosely placed a small metal pin, h, whose enlarged head keeps it from dropping through, and comes under the spring C. The hole g of each jack comes directly between two holes, a a, of the `svitch-board. The plug, Fig. 5, consists of a metal rod, D, somewhat less in diameter than the holes in the switch-board and jack and having atapered end. rlhis rod is held in the tubular insulating-handle E, adapted to receive the iicxible connecting cord or wire. The insertion of this plug in the jack from eit-herside ofthe switchboard pushes up the loose pin It against the spring C and raises said spring oft' the screw c, breaking the circuit 'from the subscribers line through the annunciator to ground, and closing, through the spring C, pin 7L, and plug D, the circuit from the subscribcrs line through the operators telephone to ground. To connect one subscriber with another two plugs joined by fiexible conductors are, as usual, inserted in the two jacks of those subscribers.

For multiple systems the spring G is insulated from the body of thejack by insulating material at k and k', as shown in Fig. 4. f In order to conceal the wires and protect them from injury w'e form grooves F F in the 9 upper and lower edges of the switch-board A, ot' such size as to contain all the wiresl l connected with the switchboard, which wires, since they are not exposed, can be smaller than usual, and we place all such wires in said grooves, making the connections from them to the jacks through holes bored in the wood of the board A. The grooves may, if desired, be filled with wax, paraftine, or similar material for the further protection of the wires. The board A is supported on suitable standards, and these standards may be made hollow, and the wires may pass through them to the grooves of theswitch-board. Thus all the wires are out of sight and are protected from contact and injury.

It will be seen that the jacks are connected mechanically only with the board A. The board A is attached to the board A by removable connections. Any suitable detachable clam ps or catches may be used. Ve have shown rods or pins G set firmly in board A, and extending throughboard A and having screw-threaded ends projecting a little from board A', on which are placed thumbnuts H. These thumb-nuts may be quickly removed and the board A then taken off, leaving the jack-plugs and their connections open for inspection or repairs, and without stopping the business ofthe exchange, for of course the operators on both sides can continue their work, as before.

The jacks are intended to be mounted in groups of from ten to twenty jacks in each group, and the back board, A', of each group is made removable. One ot' these groups is shown inFig. l. The entire switch-board will be made up ofa numberof the groups, as will be readily understood.

The metal portions of the plugs are made somewhat longer than the thickness of the double switch-board, so that when a plug is inserted its metal end projects beyond the samehoard. Thusnotonly theoperatoratthat particular point can see that that line is in use, but those adjacent can also see the pro jecting plug, and on the other side the operators can see the handle. Those operators, however, if there are any, who are too far away to see the plug, can make the usual test by inserting a plug a short distance, so as to touch the jack of the line in question, but without aii'ecting the connections of the jack.

In the arrangement shown in Figs. 6 and 7 the body B of the `jack has a screw-threaded extension, l, which is screwed into the board A to secure thejack to said board. rlhe other side of the jack Ymay have atubular extension, K, forming a bushing for the hole in board A. The test may in this case be made by touching the plug to the bushing on either side.

Figs. 8 and 9 show another form of jack which may be used it' a longerjack is desired. The metal tube L, having an aperture in its upper side, as shown at M, extends between the boards, and has a screw-threaded end, by which it is attached to board A. The screw c passes through the board A and is insulated from thejack. A long spring, N, attached to the other end of thejack, rests normally upon screw c, and the insertion of the plug from either end raises the spring off the screw and closes circuit between the spring and the plug.

Figs. 10 and l1 show still another form ot' jack, which may be called a skeletonjack, since the metal body is dispensed with. From the screw c a bracket or support, m, extends, insulated from said screw. From bracket m the spring` C extends downwardly between the holes a c ofthe switch-board. The insertion ofthe plug pushes the spring aside, as shown by the dotted lines in Fig. 10, breaking contact between the spring and the screw and closing it between spring and plug.

What we claim isl. A double switch board consisting ot' two boards placed back to back and both provided with plug-holes, in combination with jacks situated between said boards and permanently attached to one only of said boards, and the two boards being detachabl y secured together, substantially as set forth.

2. A double switch-board consisting of two boards placed back to back and having jacks mounted ou one of said boards with plug-holes 'in both boards, said jacks being arranged in groups or sections, and the back board being removable for each of such groups or sections, substantially as set forth.

This specification signed and witnessed this 21st day of March, A. D. 1887.

JOHN CRAWFORD. J OI-IN BALFOUR KER.

Vitnesses:

HOWARD P. VANNER, HARRY RITTER. 

